Spool case for bonding wire, and method of handling spool using same

ABSTRACT

A bonding wire spool case, and a method of handling a spool using the spool case has a structure capable of effectively preventing the durability and the holding of the spool from being deteriorated due to the repeated coupling and decoupling operations of the spool with respect to the spool holder while preventing the bonding wire from being contaminated and damaged due to the carelessness of the worker. The bonding wire spool case includes a base having a bottom portion and a sidewall protruded from the bottom portion. The base mounts a spool wound with a bonding wire thereon. A cover is coupled to the base at the outer surface of the sidewall of the base to prevent an alien material such as dust from being introduced. The sidewall of the base is partially provided with an opening portion. A slide coupling member is internally formed at the base such that the slide coupling member is fitted to the flange portion of the spool when the spool slides inward through the opening portion.

BACKGROUND OF THE INVENTION

[0001] (a) Field of the Invention

[0002] The present invention relates to a spool case for storing andcarrying a bonding wire of a wire bonding assembly used in manufacturinga semiconductor chip package and a method of handling a spool using thesame. More particularly, the invention relates to a bonding wire spoolcase and a method of handling a spool using the same which caneffectively prevent the durability and the holding of the spool frombeing deteriorated due to the repeated coupling and decouplingoperations of the spool with respect to the spool holder, and preventthe bonding wire from being contaminated and damaged due to thecarelessness of the worker.

[0003] (b) Description of the Related Art

[0004] Generally, a wire bonding assembly is a device for electricallyconnecting a lead of a lead frame to a bonding pad of a semiconductorchip bearing an electrical characteristic by way of a conductive wiresuch as a high purity platinum Pt wire or an aluminum wire.

[0005] The wire bonding assembly is usually provided with a spool, aspool holder, a wire feed guider, a wire clamp, and a capillary. Aconductive wire is wound on the spool, and the spool is fitted to thespool holder. The conductive wire is fused by way of the capillary and atorch bar, and welded to the bonding pad of the semiconductor chip andthe lead.

[0006] In the wire bonding assembly, the spool wound with a conductivemetal wire thereon is usually placed within a spool case, and in thatstate, it is stored and carried while preventing the contamination anddamage thereof. Various kinds of spool cases are used for that purpose.

[0007] For instance, Japanese Utility Model Publication NumberSho58-41188 discloses a spool case having a base with a protrusion ontowhich a cylindrical spool is inserted, and a cover coupled to the baseto prevent a foreign material such as dust from being introduced. Thecover is provided with a spool case, which has a depressed portion forreceiving the spool in correspondence with the protrusion of the base.

[0008] The worker grips the flange portion of the spool by hand, andfits it to the spool holder to bring out the spool from the spool case.

[0009] Accordingly, with the handling of the spool, the fingers of theworker contact the surface of the conductive wire. In this case, thewire is contaminated and damaged, and this induces serious devicefailures during the wire bonding process.

[0010] Japanese Patent Publication Laid-open No. 2000-112599 discloses abonding wire spool case having an interfacial coupling member externallyfitted around the spool flange to hold the spool, and a base capable ofbeing elastically transformed. The worker presses both lateral sides ofthe base while elastically transforming the base to remove the spoolfrom the spool case.

[0011] However, with the spool case disclosed in Japanese PatentPublication Laid-open No. 2000-112599, the base is formed with amaterial capable of being elastically transformed such that the spoolcan be separated from the spool case by way of the interfacial couplingmember.

[0012] Accordingly, in case the base repeatedly suffers the elastictransformation to make coupling or decoupling of the spool, stress isconcentrated at a predetermined region of the base due to the elastictransformation. Consequently, the base is stress-damaged while beingdeteriorated in its durability.

[0013] The interfacial coupling member, which is connected to the basein a body to substantially hold the spool, is formed with an elasticplastic material. With the repeated uses, the interfacial couplingmember becomes worn out or blunt, and this deteriorates reliability inthe spool holding operation.

[0014] Furthermore, with the handling of the spool, the worker picks outthe cover from the base, and grips the base to mount the spool to thespool holder of the bonding machine. At this time, the worker maycarelessly grip both sides of the base. In this case, the spool holdingstate of the interfacial coupling member is released so that the spoolis separated from the base. Consequently, the bonding wire iscontaminated, and damaged.

SUMMARY OF THE INVENTION

[0015] It is an object of the present invention to provide a bondingwire spool case and a method of handing a spool using the spool casewhich can effectively prevent the durability and the holding of thespool from being deteriorated due to the repeated coupling anddecoupling operations of the spool with respect to the spool holder, andprevent the bonding wire from being contaminated and damaged due to thecarelessness of the worker.

[0016] This and other objects may be achieved by a bonding wire spoolcase and a method of handling a spool using the spool case with thefollowing features.

[0017] The bonding wire spool case includes a base having a bottomportion and a sidewall protruding from the bottom portion. The basemounts a spool wound with a bonding wire thereon. A cover is coupled tothe base at the outer surface of the sidewall of the base to preventforeign material such as dust from being introduced. The sidewall of thebase is partially provided with an opening portion. A slide couplingmember is internally formed at the base such that the slide couplingmember is fitted to the flange portion of the spool when the spoolslides inward through the opening portion.

[0018] The slide coupling member has a guide rail for spacing the spoolfrom the bottom portion of the base by a predetermined distance, and acoupling protrusion protruded form the inner surface of the sidewall tohold the flange portion of the spool together with the guide rail. Theslide coupling member may have two or more coupling protrusions.Preferably, three coupling protrusions are provided at the slidecoupling member while being positioned at the portions of the sidewallplaced at both sides of the opening portion, and at the portion of thesidewall facing the opening portion.

[0019] The spool is fitted to the base by way of the guide rail and thecoupling protrusions formed at the sidewall of the base. Accordingly,the spool can be handled without directly touching it by hand. Thecoupling state of the spool is not released unless it is intentionallyseparated from the base. Furthermore, the spool can be coupled to thebase or decoupled from the base without elastically transforming thebase. Accordingly, the durability of the spool and the reliability inthe spool holding can be prevented from being deteriorated.

[0020] The coupling protrusions may be formed with various shapes whilebeing protruded from the sidewall. Furthermore, the coupling protrusionsmay be integrated into one while being spatially extended.

[0021] The portion of the sidewall facing the opening portion is formedwith a curvature identical to the spool flange. The cover has aprotrusion inserted into the inner diameter portion of the spool mountedto the base such that the central axis of the spool is maintained to bein the horizontal direction.

[0022] As the central axis of the spool is maintained to be in thehorizontal direction, the bonding wire wound on the spool deals wellwith its own load, vibration in its movement and other impacts over itsentire length so that the unintended winding or releasing of the wirecan be effectively prevented.

[0023] A prominent portion may be formed at one or more sides of thecover to keep the central axis of the spool in the horizontal direction.

[0024] Both ends of the bonding wire wound on the spool are attached tothe flange portion of the spool by way of a tape. In case the endportion of the bonding wire is attached to the outer surface of theflange portion, a notch is formed at the flange portion to pass thebonding wire. The notch may be formed at the one-sided flange portion,or at the both-sided flange portions.

[0025] With the inventive spool case, the spool can be coupled to, ordecoupled from the spool holder through sliding the base in thedirection perpendicular to the spool holder. In this way, the couplingor decoupling of the spool can be made without directly touching thespool by hand.

[0026] Furthermore, separation of the spool from the base due to thecarelessness of the worker can be prevented.

BRIEF DESCRIPTION OF THE DRAWINGS

[0027] A more complete appreciation of the invention, and many of theattendant advantages thereof, will be readily apparent as the samebecomes better understood by reference to the following detaileddescription when considered in conjunction with the accompanyingdrawings in which like reference symbols indicate the same or thesimilar components, wherein:

[0028]FIG. 1 is an exploded perspective view of a spool case with acover and a base according to a preferred embodiment of the presentinvention;

[0029]FIG. 2 is a perspective view of the base shown in FIG. 1 mountinga spool therein;

[0030]FIG. 3 is a partial sectional view of the spool case shown in FIG.1 illustrating the storage thereof; and

[0031]FIG. 4 is a perspective view of the spool case shown in FIG. 1illustrating the usage thereof.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0032] Preferred embodiments of this invention will be explained withreference to the accompanying drawings.

[0033]FIG. 1 is an exploded perspective view of a spool case with acover and a base according to a preferred embodiment of the presentinvention, and FIG. 2 is a perspective view of the base shown in FIG. 1mounting a spool therein.

[0034] As shown in the drawings, the spool 10, well known in the art,has a cylinder portion (not shown) for winding the bonding wire Wthereon, and a pair of flange portions 10′ provided at both ends of thecylinder portion. A notch 10″ is formed at the flange portion 10′ tohold the end portion of the bonding wire W. The bonding wire W passedthe notch 10″ is fastened to the outer surface of the flange portion 10′by way of a tape (not shown).

[0035] The spool case 20 for receiving the spool 10 is provided with abase 22 and a cover 24. The spool case 20 is formed with a materialbased on synthetic resin such as acryl, polyolefin and styrene.

[0036] The base 22 has a bottom portion 22 a, and a sidewall 22 bprotruded from the bottom portion 22 a. An opening portion 22 c ispartially formed at the sidewall 22 b. The opening portion 22 c makesthe spool 10 be slide-inserted into the base 22 through a lateral sidethereof.

[0037] The portion of the sidewall 22 b facing the opening portion 22 cis formed with a curvature identical to the spool 10. A slide couplingmember 26 is provided at the sidewall 22 b. When the spool 10 slidesinward through the opening portion 22 c, the slide coupling member 26 iscoupled to the flange portion 10′ of the spool 10. In this preferredembodiment, the slide coupling member 26 has a guide rail 26 a forguiding the sliding of the spool 10 in such a state that the spool 10 isspaced apart from the bottom portion 22 a of the base 22 by apredetermined distance, and a coupling protrusion 26 b for holding theflange portion 10′ of the spool 10 together with the guide rail 26 a upand down.

[0038] The coupling protrusion 26 b is formed at the inner surface ofthe sidewall 22 b over the guide rail 26 a. The distance between thecoupling protrusion 26 b and the guide rail 26 a is identical to orsimilar to the thickness of the flange portion 10′ of the spool 10. Whenthe spool 10 slides through the opening portion 22 c, the flange portion10′ of the spool 10 is fitted between the guide rail 26 a and thecoupling protrusion 26 b, thereby holding the spool 10.

[0039] Plural numbers of coupling protrusions 26 b may be provideddepending upon the kind of the spool 10 and the weight of the bondingwire W wound on the spool 10. The number of coupling protrusions 26 bmay be established to be two to six.

[0040] In this preferred embodiment, three coupling protrusions 26 b areformed at the portions of the sidewall placed at both sides of theopening portion 22 c and at the portion thereof facing the openingportion 22 c, respectively. As the spool 10 is held by the couplingprotrusions 26 b at three points, the spool holding can be made in astable manner.

[0041] Alternatively, the coupling protrusions 26 b may be integratedinto one while being spatially extended.

[0042] Furthermore, in the absence of the guide rail 26 a, the spool 10may be held by way of the association of the bottom portion 22 a and thecoupling protrusions 26 b. However, with this structure, as the slidingof the flange portion 10′ of the spool 10 is made in contact with thebottom portion 22 a, shortcomings may be made due to increase in thecontact area. Therefore, the spool holding structure is preferablyprovided with the guide rail 26 a.

[0043] Meanwhile, the coupling protrusion 26 b protruded from the innersurface of the sidewall 22 b may be formed with various shapes such as acircle and a rectangle.

[0044] The spool 10 is fitted to the base 22 by way of the guide rail 26a and the coupling protrusions 26 b formed at the sidewall 22 b of thebase 22. Accordingly, the spool 10 can be handled without directlytouching it by hand. The coupling state of the spool 10 is not releasedunless it is intentionally separated from the base 22. Furthermore, thespool 10 can be coupled to the base 22 or decoupled from the base 22without elastically transforming or deforming the base 22. Accordingly,the durability of the spool and the reliability in the spool holding canbe prevented from being deteriorated.

[0045] The cover 24 is fitted to the outer surface of the sidewall 22 bfrom the top of the base 22 to prevent the bonding wire W from beingcontaminated due to a foreign material such as dust. The cover 24 has atop portion 24 a, and a protrusion 24 b is formed at the center of thetop portion 24 a. The protrusion 24 b is inserted into the innerdiameter portion of the spool 10 such that the central axis of the spool10 can be kept to be in the horizontal direction.

[0046] The protrusion 24 b is formed with a plane shape of a circlewhile bearing a diameter identical to or slightly smaller than the spool10. The length of the protrusion 24 b is established to be the same asthe height of the sidewall 22 b formed at the base 22.

[0047] Furthermore, a lateral portion 24 c is bent from the top portion24 a. The lateral portion 24 c of the cover 24 is cone-shaped whilebeing gradually tapered toward the top portion 24 a. A prominent portion24 d is formed at the lateral portion 24 c such that it makes thecentral axis of the spool 10 be maintained to be in the horizontaldirection.

[0048] The prominent portion 24 d may be formed at a lateral side of thecover 24 standing with the opening portion 22 c of the sidewall 22 b.Alternatively, as indicated by the dotted line in FIG. 1, the prominentportion 24 d may be formed at two lateral sides of the cover 10perpendicular to the opening portion 22 c.

[0049] Accordingly, the spool 10 wound with the bonding wire W thereonslides into the base 22 through the opening portion 22 c such that theflange portion 10′ of the spool 10 is fitted between the guide rail 26 aand the coupling protrusions 26 b. The cover 24 is coupled to the base22 from the top such that the protrusion 24 b of the cover 24 isinserted into the inner diameter portion of the spool 10.

[0050] In this state, the spool case 20 is put on a table T such thatthe prominent portion 24 d is directed toward the bottom.

[0051] Consequently, as the central axis of the spool 10 is maintainedto be in the horizontal direction, the bonding wire W wound on the spool10 deals well with its own load, vibration in its movement and otherimpacts over its entire length so that the unintended winding orreleasing of the wire can be effectively prevented while prohibiting therolling of the spool case 20.

[0052]FIG. 3 illustrates the storage of the spool case 20, and FIG. 4illustrates the usage of the spool case 20.

[0053] As shown in FIG. 4, in case the spool 10 is mounted to a spoolholder 30 of a wire bonding assembly (not shown), one hand laterallygrips the bottom portion 22 a of the base 22 and, in that state, theother hand grips the lateral portion of the cover 24. Thereafter, thecover 24 is lifted upward to thereby separate the cover 24 from the base22. When the opening portion 22 c of the base 22 is directed upward, thespool 10 moves in the arrow (solid line) direction, and is fitted to thespool holder 30. At this time, the spool 10 is fixed by a spool fixationmember 32 of the spool holder 30.

[0054] Thereafter, the base 22 is pulled downward in the directionperpendicular to the spool mounting direction (indicated by the arrow)to thereby release the coupling of the spool 10 to the base 22.

[0055] It is possible to pull the base 22 in any one directionperpendicular to the spool holder 30.

[0056] With the inventive spool case, the spool is mounted to the basewhile smoothly sliding in the horizontal direction through the openingportion of the sidewall of the base so that the stress concentration isnot made at any portion of the base.

[0057] Accordingly, the durability deterioration with the conventionalspool case where the coupling or decoupling of the spool is made throughelastically transforming or deforming the coupling member and the baseis prevented.

[0058] As any portion is not worn out or stunt at the coupling ordecoupling of the spool, reliability in the spool holding can beenhanced.

[0059] When the spool is mounted to the base, the conventional spoolcase is vibrated in the weighted direction of the spool. With theinventive spool case, such a vibration can be prevented. The bondingwire wound on the spool is a extremely minute wire of about 20 μm. Sucha minute wire is correctly wound on the spool according to theprogrammed procedure of the computer. Therefore, the state of thebonding wire wound on the spool can be maintained in a stable manner.

[0060] The spool case is extensively used in various kinds of wirebonding assemblies irrespective of the length of the spool holder or thepresence of the spool fixation member.

[0061] With the inventive spool case, when the worker grips the base toseparate the cover form the base or to mount the spool to the spoolholder of the wire bonding assembly, the spool holding of the slidecoupling member is not released due to the carelessness of the worker.Accordingly, the contamination of and damage to the bonding wirepursuant to the separation of the spool from the base can be prevented.

[0062] While the present invention has been described in detail withreference to the preferred embodiments, those skilled in the art willappreciate that various modifications and substitutions can be madethereto without departing from the spirit and scope of the presentinvention as set forth in the appended claims.

We claim:
 1. A bonding wire spool case, comprising: a base having abottom portion and a sidewall that protrudes from the bottom portion, aspool wound with a bonding wire being mountable on the base; a covercoupled to the base at an outer surface of the sidewall of the base soas to prevent foreign material from being introduced into the case, thesidewall of the base being partially provided with an opening portion;and a slide coupling member internally formed at the base so that theslide coupling member is fitted to a flange portion of the spool whenthe spool slides inward through the opening portion.
 2. The bonding wirespool case of claim 1, wherein the slide coupling member has a guiderail arranged so as to space the spool from the bottom portion of thebase by a predetermined distance, and a coupling protrusion arranged toprotrude from an inner surface of the sidewall so as to hold the flangeportion of the spool together with the guide rail.
 3. The bonding wirespool case of claim 2, wherein the slide coupling member has at leasttwo coupling protrusions.
 4. The bonding wire spool case of claim 3,wherein the slide coupling member has three coupling protrusionsarranged so as to hold the spool at three points.
 5. The bonding wirespool case of claim 4, wherein the three coupling protrusions arepositioned at portions of the sidewall placed at both sides of theopening portion, and at a portion of the sidewall facing the openingportion.
 6. The bonding wire spool case of claim 5, wherein the portionof the sidewall facing the opening portion is formed with a curvatureidentical to the spool flange.
 7. The bonding wire spool case of claim1, wherein the cover has a protrusion configured to be insertable intoan inner diameter portion of the spool when the spool is mounted to thebase so that a central axis of the spool is maintainable in a horizontaldirection.
 8. A method of handling a spool using a spool case having abase with a bottom portion and a sidewall that protrudes from the bottomportion, a spool wound with a bonding wire being mountable on the base,a cover coupled to the base at an outer surface of the sidewall of thebase so as to prevent foreign material from being introduced into thecase, the sidewall of the base being partially provided with an openingportion, and a slide coupling member internally formed at the base sothat the slide coupling member is fitted to a flange portion of thespool when the spool slides inward through the opening portion, themethod comprising the steps of selectively coupling and decoupling thespool from a spool holder by sliding the base of the spool case in adirection perpendicular to the spool holder without directly touchingthe spool by hand.
 9. The method of claim 8, including sliding the basedownward in a direction perpendicular to the spool holder.